diff --git a/lib/chefspec/matchers/resource_matcher.rb b/lib/chefspec/matchers/resource_matcher.rb
index 25b188b9..d1402435 100644
--- a/lib/chefspec/matchers/resource_matcher.rb
+++ b/lib/chefspec/matchers/resource_matcher.rb
@@ -115,8 +115,12 @@ def unmatched_parameters
     def matches_parameter?(parameter, expected)
       value = safe_send(parameter)
       if parameter == :source
-        # Chef 11+ stores the source parameter internally as an Array
-        Array(expected) == Array(value)
+        # Chef may store the source parameter internally as an Array. Match the
+        # expectation against the value directly first, so RSpec matchers and
+        # Regexps work against a scalar source, then fall back to comparing the
+        # array-normalized forms so a plain string still matches a single-element
+        # array source.
+        expected === value || Array(expected) == Array(value)
       elsif expected.is_a?(Class)
         # Ruby can't compare classes with ===
         expected == value
diff --git a/spec/unit/matchers/resource_matcher_spec.rb b/spec/unit/matchers/resource_matcher_spec.rb
index aec15441..9db99cb5 100644
--- a/spec/unit/matchers/resource_matcher_spec.rb
+++ b/spec/unit/matchers/resource_matcher_spec.rb
@@ -1,5 +1,38 @@
 require "spec_helper"
 
 describe ChefSpec::Matchers::ResourceMatcher do
-  pending
+  subject { described_class.new(:windows_certificate, :create, "CN=example.com") }
+
+  describe "matching the :source parameter" do
+    # `matches_parameter?` is the private comparison that `.with(source: ...)`
+    # relies on. Drive it directly with a stubbed resource value.
+    def source_matches?(expected, actual_source)
+      allow(subject).to receive(:resource).and_return(double(source: actual_source))
+      subject.send(:matches_parameter?, :source, expected)
+    end
+
+    it "matches an exact string source" do
+      expect(source_matches?("C:/MyFile.pem", "C:/MyFile.pem")).to be(true)
+    end
+
+    it "matches a plain string against an array-valued source" do
+      expect(source_matches?("foo.erb", ["foo.erb"])).to be(true)
+    end
+
+    it "matches an exact array source" do
+      expect(source_matches?(%w{a b}, %w{a b})).to be(true)
+    end
+
+    it "matches an RSpec matcher against a scalar source (issue #980)" do
+      expect(source_matches?(end_with("MyFile.pem"), "C:/MyFile.pem")).to be(true)
+    end
+
+    it "matches a Regexp against a scalar source" do
+      expect(source_matches?(/MyFile\.pem/, "C:/MyFile.pem")).to be(true)
+    end
+
+    it "does not match when the matcher does not apply" do
+      expect(source_matches?(end_with("other.pem"), "C:/MyFile.pem")).to be(false)
+    end
+  end
 end